


Poisoned Love

by EmeraldWriter, SaJellyfish



Category: Undertale (Video Game)
Genre: Dacryphilia, Emetophilia, Impregnation, Infanticide, Kidnapping, Mpreg, Sanscest - Freeform, Underfell, Yan Sans, Yandere Sans, brain washing, kustard - Freeform, love potion
Language: English
Status: Completed
Published: 2017-01-19
Updated: 2017-01-19
Packaged: 2018-09-18 11:59:53
Rating: Explicit
Warnings: Graphic Depictions Of Violence, Major Character Death, Rape/Non-Con
Chapters: 1
Words: 7,999
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9383999
Author URL: https://archiveofourown.org/users/EmeraldWriter/pseuds/EmeraldWriter, https://archiveofourown.org/users/SaJellyfish/pseuds/SaJellyfish
Summary: Ut!Sans somehow wakes up in Underfell. Fearing, Ut!Sans will replace him in this universe, Uf!Sans attempts to poison him...





	

**Author's Note:**

> Please follow us on Tumblr! 
> 
> ( LazySintastic13)  
> ( SaJellyfish)

Exposed to the harsh snow and wind of Snowdin’s weather, the small guard station sat at the end of the path, dusted in snow and dirt. From a distance, no one would have ever thought a guard was at the station. It looked abandoned, save for the fluff of wool from Sans’ hoodie. He looked pathetically small, shrunken into himself to preserve what little heat his bones could manage.

Boss tutted his teeth. He had been in a good mood, thinking Sans was taking his job as a sentry seriously but he had just fallen asleep again. He was easy experience, it was miracle no one had dusted him with his defense lowered. He made a mental note to lecture Sans about that later. For now, getting him out of the snow was his only priority. He strode over to him, shaking his shoulder to stir the lazy monster awake.

“Sans.  _Sans!_  Get up. Your shift is over.” Papyrus looked down at his brother, the striking blue jacket seemed out of place… since when had Sans bought that?

“Ten more minutes bro- I’m going for a record. heh... but it's so easy.. I can do it in my sssslll….zzZZzzZZzzz” The monster dozed off and Boss raised a nonexistent brow, that voice… It sounded like Sans… but less grainy. Less… fearful?

He began to wonder why but his thoughts were cut short when he heard footsteps behind him. Papyrus spun on his heel, summoning his magic to attack the monster that had snuck behind him but all he saw was his brother. Sans stood awkwardly, with his hands in his pockets. His face is torn between confusion and nervousness as he gazed at the bone attack aimed towards him.

“W-what are you dd-d-doing  Boss?!”

Papyrus turned back to the sentry station, then back to his brother? Something wasn’t right here. This was some sort of trap set up by Sans, he had assumed, that perhaps a stuffed sweatshirt or a paid off monster was to play that role.

Tiredly, he pointed a gloved hand at the other Sans but decided against it. Instead he focused his attention to his … brother. “Sans … Why are you away from your sentry post in the first place?”

He saw his brother falter and began to sweat.

“I, um, that is—”

“Well, never mind that. No doubt you were elsewhere that's of no importance. Though, I must say, I didn't think you've gone through such lengths in skipping work and had even hired someone to take your place.” It was convincing too. But he didn't let it be known how proud he was of his brother for the smart move regardless of the intention behind it.

Sans cocked his head to the side, more confused than ever. “ … I didn't hire anyone though.” He didn't argue about skipping, it's what he always did anyway. Though he never hired anyone as a stand in for him. Too much of a waste in money, time and energy. Plus, there would be no monster he knew that could be convincing enough to even get the job right.

So the question now is,  _who_ the fucking hell is the monster on his station?

Papyrus’ eye sockets widened and sharply turned to the sleeping figure. His magic flared as he growled; summoning his bones, ready to look as threatening as he was feared around the town.

Sans attempted to move forward, only to be stopped by his brother in a commanding voice. “Stay where you are!” And he did, only for a short time before teleporting behind the imposter.

“ _Sans!_ ”

It was rare for his brother to not listen to him, but he cursed his brother’s curiosity. Similar to his own when he was just a baby bones, he now understood the troubles his brother had to deal with. But now was not the time to be naive in this situation. The imposter could be a danger to them, regardless that the latter looked like his brother.

“This is no time to be—” but his words died out when the stranger began to stir.

The skeleton brothers became tense, focusing all their attention to the one waking up. That is… if he ever did wake up. The small skeleton seemed content to sleep, completely unaware of the threat that loomed above him. Sans took a step forward, phalanges barely touching the back of the other’s hoodie. He yanked it down and jumped back as soon as he did, cautious of a counter attack. Yet, the monster remained still.

“Is he  _mocking_ us?!” Boss screeched. He stomped angrily towards the station ready to challenge this warrior who dared sleep through the great and terrible Papyrus’ inquiry. Then, he set his eyes on the face of the sleeping monster. The shadow of darkened blue around his eyes and the dull flattened teeth grit together in a smile… He hesitated.

A moment later, Sans peered over at the stranger as well. The two stared; baffled at this monster.

“Woah–it's...  _Me_?”

“Ridiculous… we’re the only skeleton monsters here.” Boss grabbed at the scruff of the blue hoodie up in one hand and pulled the slovenly dressed skeleton up. “Weak.”

“Sh-should we bring him back B-Boss? Int-te-terrogate ‘im?” Sans paced around anxiously, unwilling to unsummon his attack. He eyed his Boss and the monster that dared steal his look. There was something in Papyrus’ expression he didn't like…

“He’ll make an excellent pet!”

Sans nearly spit up. He was about to protest when his brother began to walk off back to Snowdin. He carried the sleeping skeleton under his arm like it was a football, and he refused to let go despite the nasty stares he received from the villagers around them. Sans followed closely from behind, unable to stop his bro once he made up his mind. To his surprise, not a single monster attacked while they truck the town. They made it home in one piece, but rather than go indoors, the boss kept walking towards the shed.

The shed was frozen over. Mainly used for tools and a holding cell for Boss’s imaginary victims; it hasn’t had much use. Insulating it would be a pain and it lacked furniture of any kind. Closing the door seemed to make the room slightly tolerable to the cold. Boss beamed, choosing a selection of chains from the wall and binding the copy to a stake in the ground. The imposter looked like a puppy on a leash. It would be funny, if Sans weren’t concerned for his own safety.

Now that they’ve covered enough precautions, it was time to wake their new ‘pet’. Papyrus did the honours himself and shook him roughly by the shoulders. If he was going to be honest with himself though, because of the similar appearance to his Sans, he didn’t have the heart to harm their captive.

“Wake up!  _Wake the fuck up!_ ”

The sharp intonation in Papyrus’ voice made Sans cringe slightly. He wondered how in the world could his copy sleep could actually sleep through that. The answer was, he didn’t.

Their ‘pet’ finally woke up, and the latter did so, much to their growing irritation, slowly.

“Hmm?”

Sans was startled at how, even their grumbles were similar. The difference was there though, but that wasn’t really anything to be relieved about.

“... Huh?” White eye lights stared at them, perplexed. “Um, hi?” The moment he tried to wave, he stopped. Hands moved towards his neck to grab the collar.

The air suddenly changed. Heavier and colder than before and despite the bounds, Sans knew that their captive was strong—dangerous. All of his senses were telling him to take Papyrus and just bolt out of the room.

But he didn’t— _couldn't_.

His doppelganger had not done anything that would incite it and his brother; despite all that he taught him in reading the change of mood, had his dull moments. This was unfortunately, one of them.

“So …” The stranger’s tone was still friendly, but Sans detected a threat beneath them. This monster was testing the waters. “… Am I missing something here?” Though the timber of his voice relayed confusion, his eyes darted around the room to search for some sort of clarity. His magic hummed in the air. Despite not knowing the full situation, this monster wasn’t dense to the presence of danger.

No one answered.

The petite skeleton eyed the tools on the walls; daggers, shovels, various lengths of chains, the same to adorn his neck, and sharp looking doodads that he couldn’t even place had rusted to the iron walls.

The room itself appeared like a cage, something his own brother would have made since the cell bars had been spaced so far away that any monster could walk through it with ease. Its practicality was questionable, as was the large menacing figure with his brother’s face. His magic waned at seeing the familiar appearance and yet knew at once that this person wasn’t his sweet little brother.

It couldn’t be … and the monster beside him was— _well_ —him.

Another Sans with a cracked dome of a skull and red lined eyes. From his spot on the floor the monster makes a small heckle, having imagined the monster put eyeliner on just for this event.

To the two Fell brothers, his small laugh wasn’t received well. It was deep and menacing. They stood ready for an attack, hyper aware that neither had seen what their ‘guest’ is fully capable of.

With a lump in the back of his throat, the stranger turned his attention back at the taller of the two skeletons. The one that resembled his brother.  He attempted to stand up and greet the two properly only to be tugged backwards by the taut chain. Suddenly, his position is made strikingly clear.

He was a prisoner.

His magic heaved against the surface of his fingertips, drawing forth a weapon to protect himself. The dark swirl of blue magic ran through the bone construct, raised towards his alternates. At the moment, he did not care where he was or who these people were.

“Where’s Papyrus!?”

Taken aback by the fierceness of their captive’s attitude, Papyrus balked almost immediately.  _Him?_ Why was this one referring to him in such a friendly manner? He had already established that the latter was no more than his brother’s look alike, so he bore no connection to this skeleton.

Sans on the other hand, had his fear heightened. Fear for both his brother and for himself. The chain wouldn’t hold. And he felt that if he didn’t take action now, then—

“ _I’m_ Papyrus and I can assure you that I have no relation to you whatsoever. You’re being detained here for not only impersonating my brother, but even going as far as to address  _me_ , the great and terrible Papyrus so familiarly. As punishment, I was merciful enough to make you my  _pet_.”

The moment he finished, there was a palpable silence where no one moved. No one until—

_Boom!_

It was all so sudden that the two brothers weren’t able to react. In one swift second something had whizzed past their head. The next thing they knew was that a large bone had buried itself in their wall.

A metallic clank hit the floor, forcing the two to snap their heads back towards their pet, his chains were broken. The copy sent the two a fierce glare, puffing his chest out as he stood tall. “If you fuckers think I’m going to be that easy. Think again.” He used his magic to form a dagger and aimed it at his neck to rid himself of the damn collar. The leather choker clattered to the floor and the stranger looked defiant. “I’m  _no one’s_ pet.”

And he left.

… He  _left_.

Papyrus stood there for a good amount of time, still processing what just transpired.

Sans on the other hand, was livid. This copy of him was going to be nothing but trouble; he would ruin the image his brother had worked so hard to build and if a monster mistook the intruder as Sans, he’d be held responsible for any actions the other did.

But what could he do? A fight was out of the question. That would bring only bring unwanted attention and he didn’t need Alphys nor Undyne to get on their case.

Sans gritted his teeth. He was not one for violence, surviving this long involved running away often; however, he wasn’t innocent. Papyrus never knew of it, but he had to stain his hands with blood and dust in the past.

Teleporting into his room, he peeled a plank of wood off the floorboard to retrieve a box beneath it.  _This doppelganger of mine was going to be trouble._  He repeated to himself over and over again as he held the glass vial in his hands.  _He needs to disappear._

* * *

 

The escapee leaned against a tree, breathing deeply to calm the erratic beating of his soul. “That could’ve gone better.” He said to himself, slumping to slide down and sit on the cold ground.

“Heh. Looks like there's  _snowflakin’_ way outta here.  _Icy,_  I’ve gotten myself in something bone  _chilling_ , this place is full of stone _cold_  killers.” The puns served to calm his nerves a little.  He takes a deep breath and pulls his hoodie up, sure he’s away from danger.

He had made sure to hide when he teleported all around the town. He needed concrete evidence to his speculation, and now, he didn’t know whether to rejoice or not when he was correct. This wasn’t his world; not his Snowdin, not his house, not his Grillby’s, and not his Papyrus.

He pulled his hood over his head, his hands clutching at its sides as he willed himself to stay strong. His brother would encourage to never give up. He’ll find a way to get back to his own world. Somehow.

His musings were cut short when he heard the familiar ‘pop’ of teleportation and looked at the intruder.

“So this is where you were.”

It was Papyrus.  

Surprise was evident in his features for the skeleton never knew his little brother was even able to do it, regardless that it wasn’t his own.

“You can refuse to be my pet but It’s not as if you can go anywhere. My brother and I are the only skeleton monsters here, it's easy to pinpoint your magic signature.”

The truth to those words weren’t exactly easy to swallow.

“Furthermore ... “There was a brief moment of softness in the tall skeleton’s face that fugitive caught before it went back to its usual hardness. “I can’t have my brother’s look-alike running amok in the town. It would benefit us both if you returned with me immediately.”

“... Are you offering me a place to  _chill_?”

He could see the twitch in the other’s eye, and couldn’t help grinning.

Papyrus let out an exasperated sigh. “I see that you’ll be as insufferable as my own brother.”

“Not about to give the  _cold_  shoulder are you?”  The glaring was fierce, but he took it all in stride.

“If you don’t get your boney ass up, I’m going to make sure you freeze out here and become the  _sansicle_  you deserve to be!”

“Woah. I think you really need to  _cool_ down there, no need to get all  _fired_  up.”

Papyrus threw his arms in the air. “If you’re not going to come, then freeze for all I care!”

“Geez. I was just trying to  _break the ice_.” The fugitive got up to follow his stomping companion. Looks like there was some hope for him at least.

* * *

 

Sans was surprised to see his brother and copy enter the house together. He was about to go search for them when he found Papyrus gone from the shed. He was just coming down the staircase when they came in.

From the looks of it, some conclusion seemed to have been reached, sensing the change of mood between the two. He ran up to his boss, tackled him, into the briefest hugs in history. He’d thought for sure his double would be intent for a fight and when Boss left, Sans feared the worst.

Boss tapped the top of his head slightly, acknowledging the small gesture of a hug before the two of them separated and faced the blue copy. “Sans, this little shit is going to stay with us for a while.”

Sans stared at his copy. It was still jarring to see an unmarked version of himself, with bones all pale and smooth. The monster would have to be an immensely skilled fighter to never receive a scar… Sans wondered if the other was just toying with them. It wasn’t uncommon for monsters to trick each other. Monsters would play victim and after earning trust would later stab them in the back or dust a monster in their sleep… Sans absentmindedly touched the vial in his back pocket.

“Hello, friend.” He bit back the callous tone in his voice. Boss may be fooled by this sweet little shit but he certainly won’t. He’d have to protect his brother.

His double leaned forward, already so bold as to reach for his neck. Sans flinched; his mind racing to the possibility that the other monster was trying to strangle him but it stopped just short of his neck. Instead, it gripped the metal tag attached to his collar and pulled it forward.

“Heh.” The look-alike chuckled. “So you’re Sans too—weird. Nice to meet me.”

Sans tugged his collar back in place and secured it around his neck as a safe keep. When he looked back up, the copy was already gone, exploring the odd differences in the household.

Boss acted as his tour guide; hovering around him, following him from room to room. He had stopped every so often to explain random shit. The blue Sans noticed small changes in the house and went on to say them out loud, like the different colored sofa and the placement of a lamp from left to right. Then there were bigger, obvious changes, like the staircase with no guard rail and the kitchen with knives stuck in the ceiling.

“We’re taking bets to see how long it takes to fall down.” Boss remarked. “Loser has to wash the dishes.” In a grand gesture he motioned to the overflowing sink, where stacks of plates and cups towered in perfect balance.

Sans felt sick watching the two interact. He knew it meant nothing… but boss was playing host to his imposter. Boss was acting friendly and answered questions without pause. This monster could be trying to replace him… or kill them both. Sans gulped dryly.

“So… pal. Where you from?” Sans tried to edge his way back into conversation. He made his tone friendly and tried to be charming while the skeleton rambled about how he had lived in Snowdin the last couple years.  _An obvious lie,_  until he heard things like resets and time travel. The intruder mentioned something about his kidnapping too and sternly turned towards them, claiming he’s not a pet. Confirmed. This monster was crazy  _and_ weird.

“Haha… great story, guy.” Sans faked a laugh and tried to move the conversation but Papyrus interrupted him.

“That’s rude Sans 2, you have to address Sans by his name!”

“... Sans 2?”

“Well, we wouldn't want our guest to feel uncomfortable now would we?”   

_This monster needed to go._

Sans scowled. He skulked back to the kitchen where he wordlessly had begun to scrub the jenga tower of dishes. Papyrus would have been overcome by surprise if he weren’t so enamored with their guest. It was the first time they’ve had company over and boss was fascinated by this  _fake_.  

Sans listened idly, loathing the other for having taken his name and his face. That was excusable… somewhat. But when the fake stole the attention of his boss…  _That's going too far._  Sans ground his teeth together, rummaging around the kitchen for something he can make into a half decent meal.

“YOU READ FLUFFY BUNNY?!” The outburst of laughter from boss warmed his heart. “Only babies read it. That's why Sans 2 reads it for me every night.”—and just as quickly as it came, the sentiment disappeared.

_Well, at least they weren’t fighting._

Sans turned his back to the living room and faced the stove. Dinner was a mixture of instant oatmeal and a ramen packet he had found in the cabinet. The meal is split into three different bowls of watery goop. Normally Boss would do all the cooking, but Sans can’t ask him for help. He heard the voracious laughter a room away, and it stirred something in his gut.

Boss never laughed.

He thumbed over the vial in his pocket, wondering if he’s particularly jealous or dutifully protecting his little brother. If the fake just died from poison, he wouldn’t have any signs of putting up a struggle before he dusted. As a plus, an indirect kill won't raise Sans level and—Sans thinks—  when boss asks what happened he can say the monster choked … Then he’d have a nice long chat with boss about letting strange monsters in the house…

He sets up the table and laces one of the bowls with the poison. The liquid has no fragrance, or color. He stirs it into the bowl and calls out to the two in the living room.

“Grubs ready.” He sat Papyrus down at once and took the other chair for himself. The copy sat at the last one, in front of the bowl laced with poison.  “Eat up.”

“... Eat  _ramen_ oatmeal? Yeah… no thanks.”

“Eat.” Sans growled. The nerve of this guy.

“No. Why would I eat this shit?”

He couldn’t control his temper any longer, and  _exploded_. “BECAUSE  _YOU_ ARE A  _SHIT_.”

_Slam!_

Boss had banged his hands on the table before he got up from his chair. “You two need to learn to fucking  _get along_ with each other. I’m going to leave and by the time I come back, you better be  _nice_ to each other!”  He stomped away from the kitchen table and up the stairs. “You have FIVE MINUTES.”

There was a harsh slamming of a door that made the other occupants of the house wince, and the two Sans stared at each other.

Sans got down to business immediately. “What's your aim? Trying to snuggle up to my bro?”

“You creeps are the ones who kidnapped  _me!_  I don't want to be here either,  _Red._ ”

Sans paused at the name. He supposed it was an improvement from Sans 2, but for the other to presume his new name was slightly annoying. According to the other monster, he was a time traveler. This wasn’t even  _his_ world. So shouldn’t  _he_ be considered the original? No matter. The other monster would be dead soon anyway.

Sweaty and nervous, Sans huffed as he sat down. “Just … Just eat.” He just needed to wait.  _Just a bit more. Have some patience, Sans._ He tried his best to look as sullen as possible.

“...So you cook?” His fake poked around a noodle with the blunt end of his fork. “That's cool, I guess. Practice really helps. When my Papyrus just started cooking he also--”

“I said, just eat.”

He can feel the other’s stare at him. “... You ... really don’t like me, huh.”

Red banged a fist on the table. “I  _hate_ you! You come in here, coddle up to my brother, with my face, and  _my_ name. Why would I even be  _nice_ to you?!”

“... Sorry.”

Red looked up at the skeleton, and found himself deflating when the sadness was evident in the other’s expression. Their gaze met.

“If anything, I’m just probably trying to cover up that—”

“ _Shut up!_ ”

“...”

“I don’t want to hear it. You won’t win me over with your sob story.”

“... Okay.”

When Red looked up, it was as if time had slowed for him.

He watched as his double dipped his spoon into the soup. He watched as it was lifted and neared the mouth. And he watched when the latter took the mouthful and  _swallowed_.

That was all he did—watch.

Tense moments passed, and he waited for the latter drop or do  _something_  but as the alternate Sans continued to eat his meal with disgust evident in his features, Red wondered if he had been tricked by the vendor years ago.

He looked down to his own bowl when he hears the loud thunk of bone hitting porcelain. Red jerked up at the sound. The other was face down in his bowl, unmoving.

He did it …

He killed his fake.

Red’s soul thumped hard against his chest. He’d killed before for Papyrus, it wasn’t anything new… but he still hated himself for it. He reminded himself that it's okay. Its kill or be killed and he had to protect his brother from enemies. His breathing was becoming erratic. He placed a hand on his chest to calm himself.

_It’s okay. It’s going to be okay. I’ll just tell Papyrus that—_

The Sans sat upright, making Red jump in his seat. He was alive! He cowered when his own red eye lights met with deep blue ones. Oatmeal like pudding dripped from the curves of the others face onto the table.

“...You… okay there?” Red mumbles. He’s unsure if this is just an after-effect of raw nerves, twitching the other’s corpse or if the other was conscious but when he stared at him like that he just felt off.

From the other side of the table Sans is quiet. His eyes left open staring at Red. The monster hadn’t turned to dust, had he merely fallen? He felt half tempted to get up and poke the other when the skeleton suddenly lunged across the table, face full of oatmeal smacking teeth with his own. The clatter of bone on bone make both of them wince in pain. Their bowls clatter and smash to the floor.

“What the hell are you—!!” Red is cut short as a summoned tongue is pushed into his mouth. The slick blue appendage lapped at the oatmeal on his chin. The other was fully on the table, the meal forgotten.

Sans wiped at his face, trying to get the stick of oatmeal away from his eye sockets and heaves another long drawn out breath to devour the others mouth. He fumbled for a moment, his attempt to use the collar of his shirt to wipe at the goop proving futile. Soon, giving up on his coy act, his blue copy decided to just pull his entire shirt off to use as a rag.

Red started to panic, unsure of why the other suddenly jumped him. Exposed in the well-lit kitchen, the succulent pale white bones fill Reds vision. They are unmarred and beautiful, contrary to his own. His eyes are drawn to the dripping blue soul that pulsates in his ribcage, and then up to the lusty expression the other has for him.

He pushes back on his stool, the wooden chair drags across the kitchen tile making a loud fart noise he would have once laughed at but now all he can think of is—

“What the  _hell_ is this?”

Apparently the notion was also shared by his brother, as Papyrus stood in the doorway of the kitchen. 

 _Stars, thank fuck Boss was here._  “Boss!”

“Sans 2, what the fuck is going on here?!”

Red moved towards Papyrus, using the latter as a shield to get away from this psycho as soon as possible. Boss cradled his hand in his, their entwined fingers was calming to Sans. Boss would fix this right? The look of relief and glee did not go unnoticed by Sans, and directed his glare towards his  _enemy_.

“You’re in the way.” The intruding Sans looked between the taller skeleton and his lover. Lover? Yes, lover. Red was his. They were in love. So why was he running away? They had been through so much together. He still remembered the day he met Red—their first meal together, their first kiss; memories that were so fresh in his mind, almost like they had happened only minutes ago.

But that couldn’t be, right?

His mind felt so jumbled. He just knows… Red was so close to him and he felt so hot. Sans had been burning from the inside out. His soul felt like it was on fire. So why was Red running away? Didn't he love him? Why did he feel so wrong about thinking that? His soul churned.

“Boss—I fucked up. I tried to poison him… but—” His eye sockets widened, his brother’s soul was brought forth. There was a blue heart that pressed against his brother’s rib cage, its rhythm steady and strong until the moment blue magic took it over completely.  Red screamed when his brother was suddenly flung away from him. “ _Papyrus!_ ”

The tall skeleton hit the side of the wall hard enough to tear through the wallpaper and plaster. There was a sickening hollow pop when the back of his skull cracked against a beam. Boss’s magic was instantly gone, disappearing into the air as he’s thrown again to the other side of the house. Red ran out and grabbed Sans’ hand, trying to stall his attack, and was relieved when Boss slumped to the ground like a puppet with its strings cut. His soul quivered, still alive.

“You’re… you’re holding my hand♥!!!” Sans blushed. He reached out for Red, enveloping the skeleton in a tight embrace. It felt like a strangle hold more than a hug. Red fights to be free from the other.

“Sans? Let go! I’m sorry. I tried to poison you, but I think it was an aphrodisiac instead or something stronger because… you’re acting a bit... aaanngh!”  His words were cut short as a tongue dragged over his vertebrae. Red shivered as the saliva cooled in the air.  

“Red, I need you.” Sans panted. He directed Red’s hand under his ribcage, encouraged him to touch and tease his soul. Red was flustered, seeing that expression on his own face was…

But no—Papyrus was hurt and this monster was a horny mess of hormones. He could deal with him later, but for now, he rushed toward his brother, or he was about to, when the same blue heart appeared on his own chest and lifted him up.

“W-Wha—”

“You’re  _mine_.” The possessiveness underlying the commanding and harsh tone made him freeze. Slowly, he turned his head, and saw that Sans was  _livid_. “Don't you  _dare_ run to any other man! Aren’t I good enough for you!?.” The monster was practically in tears, blue trails of magic streaked his face.

“What the  _fuck_  are you talking about?! Let me go! Paps needs my hel—” His futile struggle was cut short and his breath was caught in his throat when he was suddenly staring at blue eye lights right in front of him.

“ _No one will separate us again._ ”

The blue magic pinned him to the ceiling, Red struggled in the grip. He summoned his own magic and tried to take back control of his own soul but it was pointless, he couldn't fight. He never was able to control his magic with the same proficiency as his brother. The most he could do was teleport but even now that seemed impossible to perform.

He tried to use blue magic on the other Sans. He knew it was pointless but he had to do something! Tears were forming in his eyes and they slid down his cheekbones for all he could do was helplessly watch this  _monster_ head towards his brother.

He watched him stand in front of Papyrus.

He bent low, kicking the trash that dared disturb him and his lover. Somewhere in the back of his mind, Sans thought he couldn't do this. He couldn't kill a monster with the face of Papyrus. His precious little brother. But that small voice was hushed by the drug in his system. All he needed was Red. Red was the only one that mattered and no one would take him away from his precious partner.

Boss, lifted an eye light up to the figure in front of him, drifting somewhere in and out of consciousness as the back of his skull was cracked from the impact. He made out enough of the shadow to recognize it as his brother. But he wasn’t sure...

“S-Sans?”

Red looked down at his brother, the sound was weak and he almost missed it. His brother was calling for him… and all he can do is watch. Red started to yell. 

“Shh, love♥,“  Sans pressed a finger to his teeth to silence the other. “It will be over soon and then we can be together forever.”  Sans summoned a weapon similar to that of a scythe made of bones and magic as his brother looked up at his killer. He watched as his precious little brother looked to him just as the devil readied his attack.

A small red bone flew out towards them both, missing its target and instead lodging itself into the red pulsing soul in Boss’s ribs. Papyrus spits up, looking up at his brother on the ceiling and at the copy in front of him.

“I’m s-sorry, Sans.” He smiled weakly. “I’m selfish… I don't want you ...  to level … up.” He laughed, twisting the femur in his own chest. The bone dissipated, its host’s magic exhausted. Boss slowly started to dust as Sans stood over his body, a satisfied smirk placed on his ever-present smile.

“Finally.” His blue copy laughed. He lowered Red from the ceiling and the latter crumbled into his knees, unable to stop the tears that rip through him.

His brother was dead.

His brother was  _dead_ and all he did was— _watch_.  

The monster before him might as well have delivered the final blow. He was enveloped in another warm hug as the monster took hold of him once more, hushing him in soft murmurs as if it would do him comfort; telling him how much he loved him, how they’re going to get married …

Red hardly absorb what was happening… He only knew that someone was hugging him and he clung on to this person—desperate to quell the tightness in his chest. He sobbed painfully into the blue parka, wailing his brother’s name in agony as the night rolled on.

Sans dug his hands under the thick sweatshirt Red wore, eager for more than just a simple hug. He finally had him to himself; finally could touch Red without him flinching away.  He stroke at the base of his spine, humming to himself while he commits to memory the feel of the other’s frail trembling body in his hands.

“Don't cry Red, I’ll be gentle♥.”

He tilted Red backwards until his head hit the floor, practically inches from the dust trail left by his brother. They lingered in each other’s touch. Red winced and he closed eyes, letting the other touch him as he mourned for his little bro. He was too tired to fight back. He didn’t even want to anymore.

He let his little brother die. He was trash. Lower than trash. He tried to poison this intruder and only turned him into more of a monster than he already was. His soul churned with guilt and self-hatred. If he hadn’t interfered, then maybe Boss wouldn’t have died. It was his fault, all his fault and—

The sick acid of bile ran through his manifested throat, it spilled up through his teeth and seeped in the crevices of bone. The smell alone made Red feel worse. His body buckled upwards, heaving up vomit into the gape of his neck. He wanted to turn and just puke all over the floor, but his legs are pulled up towards the other's shoulders.

When had his pants been removed?

“This part hasn’t formed yet…” Sans hummed. He swirled a fingertip in the sick pool on the floor and rubbed the slicked finger against the sensitive pubis bone. Red arched, a mess of snot, tears and vomit stuck to his clothes. He was almost glad when the damp clothing is pulled from him and he was left lying on the living room carpet, bare.

Sans’ skilled fingers worked him up, stroking the side of his femur in time with the slick digits rubbing against him. He knows exactly where to touch, exactly where Red’s sensitive bones ached. Wet squelches filled the silence.

His magic began to respond to the touch and protested against the intrusion, tightening as Sans mercilessly stimulated the mound of ecto-flesh. Red couldn’t hold on, throwing his head back to make an unintelligible sound of hiccuping and moaning as Sans bent down to lap against the pale bone.

Red whimpered, his eyes snapped open long enough for him to watch the front of Papyrus’ face dissolve to dust and shatter, leaving a hunched figure against the wall, its head separated from its body.

It wasn’t real though. Sans thinks. His bro couldn’t be dead. It was impossible.  

The flat of a tongue dragged against his hips, and Red tried to scramble away. He searched for relief when there was nothing but the rough carpet dragging across his back with Sans holding onto his ankles; his grip was tight enough to bruise bone.

“Don’t look at him.” Sans whispered huskily, “Only look at me♥.” The vibration of words against sensitive flesh made his partner choke up a whine. His knees trembled together; held open only by the forceful grip Sans displays them with. 

The combination of red and blue marked them with a purple hue where their magic mixed. Sans reveled in the color, wanting to taste more and more of it until Red cried out mid orgasm and whimpered for him to stop;  _begged_ him for it. And Sans would never refuse his precious bride. Not when Red was practically pleading for him  _not_ to stop.

A word of difference.  

It didn't matter. Red loved him. He loved Red. They were perfect together and—and—

Sans can hardly remember who he was before he met Red.

And Red can hardly remember who he was before he met Sans.

He couldn't hold back any longer, Sans got up and freed his erection from his clothed prison. He lined himself up just right to slam into the small opening he’d worked into Red’s writhing body. They both screamed, lost in the sensation of pain, and of pleasure.

Red shut his eyes long ago. He didn’t want to see his rape, didn't want to see his brother turn to dust,  but at the same time closing off his sense of sight only made him sensitive to the attacks on his lower half. He spits up bile, choking up whatever remained of his dinner and moans, shamefully, into the nook of his elbow. His toes curled, pulling at the blue sweater Sans wore, trying to grind his heel into something tangible so he can keep his mind levelled but it was too much for him.

His mind was numb as he shuddered through a second orgasm. Sans doesn’t stop, still grinding up against the pillar of spine through the ecto jelly of his stomach. Red can barely hold on, with his eyes half-lidded he rode through waves of pleasure as Sans rutted up against him, swirling his seed deep inside his engorged stomach.  

“S-sto—stop.” He moaned weakly, as he stared at this stranger through bleary tears, and watched as he found himself stained in the new violet color. Sans clanked their teeth together, crushing his protests and swallowing his throaty moans as he filled him again, and again with his seed.  He has to—has to make Red _his_  and  _mate him_  until he knew it too.

The taste of semen and vomit mixed in their saliva; it was vile, and Red wanted to push away in disgust. He could barely tolerate himself right now… And yet, Sans was desperate for touch, lavishing in every gross movement Red made. He bent him to his will and filled him with his love. Now, he lied in his arms in a restful sleep while Red stared at the dots on the ceiling and racked his brain to remember who he was…

Where he is?

Why did his legs feel so moist?  

These thoughts swirled in his mind, never receiving any answers for them before he too, succumbed into the lull of sleep.

* * *

 

It’s been weeks since anyone had heard of the skeleton brothers. Monsters were left to fend for themselves, monsters died everyday no one bothered to do anything about it. No one bothered to ask questions. No one questioned the new skeleton living in Snowdin and no one cared.

Red sat on the bed in his room— _their_  room. It used to be someone else’s but Sans had refurbished it early on. He did the same to his old room, changed it to a nursery with gleeful bright colors and toys. He’d gone to change the inside of the house, fixing the rails, removing traces of dirt and belongings…

Red looked down at his growing stomach, feeling the presence of the little one, its soul beating—alive. He wasn’t sure at first if he wanted to keep it but at his lover’s insistence, he decided that maybe it wouldn’t be bad. For weeks Red had thought the house felt empty… like something was missing. Maybe a baby would fill that void. They could be one big happy family…

The skeleton sighed, rubbing his head, feeling an oncoming headache again. It’s been happening often enough and he wondered if there was something wrong. His lover had been concerned for his well-being. He had been providing medicine to help ease the painful headaches. It was effective, and rid him of the ache, but something felt  _off_.

He couldn’t put his finger on it. He wished he could ask someone… Someone who always protected him and was by his side growing up. His brain told him it was Sans who did that… but his head hurt when that answer came up. Sans would hold him in his arms and hush away the pain. The company was much appreciated.

The knock on the door took him out of his musings as Sans came into the room, a glass of water and pills occupied both hands. “Hey, how are you feeling?”

“Same old, same old.”

“Headache still persisting?”

“Yeah.” Red sighed as he closed his eyes when Sans planted a kiss on his head.

“Don’t worry, love. I got your medicine here.”

Red smiled, “Thanks. Sorry for the trouble. I don’t know why it keeps coming back.”

“It’s no trouble. You know that I’d do anything for you.” He placed a capsule into Red’s hand and the latter grabbed for the water. “Besides, I doubt it’s anything serious. If it were, I would’ve rushed you to the hospital by now.”

“Yeah … Yeah, you’re right. I’m probably just being paranoid.” And with that, he popped the pill and drank the water.

Once Sans took the glass and placed it on the counter, he sat by his lover’s side. “Is our baby doing okay?”

The mention ‘our’ somehow always made him nervous. And it confused Red to no end as to why. Was he that fearful of starting a family? He didn’t think he would’ve been the type to turn away at the chance of family. He mentally noted, there was really something wrong with him for staying so negative. He tried to be positive, so his partner would smile and everything would be okay. “It’s doing fine. Hasn’t kicked or anything yet. I can feel its soul beating...”

“Heh, must be an interesting experience.”

“No doubt—” Red felt that he was going to puke, just like he does every now and then. Hastily,  he left the room, locking the bathroom door and practically puked his breakfast down the pearly white bathroom bowl. White like bones. White like dust?

The thought hurt his head and he retched again into the toilet. He could barely hear the knocking on the other side of the door. “Do you need any help?”

“N-No. I’m fine!” He rested his head against the seat to catch his breath.

“All right. If you’re sure. I’ll just be downstairs in the kitchen.”

Red didn’t bother to answer back; he heard the footsteps become fainter and fainter, until it was completely silent save for his short breaths.  So much for his medicine... it hardly had enough time to absorb in his stomach before he puked up.

When he was able to get his bearings and his stomach had calmed, he slowly stood up. However, he didn’t anticipate for his legs to be so unsteady and fell to the ground, banging his head hard against the wall. A small indent is left in the wall.

“Fuck.” His mind was all jumbled up and he didn’t have quite the strength yet to get back up. With a hand nursing his head, he stared at the bump in the wall. He remembered seeing something similar in the living room that had indented the wall, tore through the wallpaper and plaster…

_Papyrus._

He remembered … seeing a bone hit his brother’s soul—plunging into it.

He … remembered … Papyrus apologizing to him, and he watched him … slowly dust away.

Red let out a gasp when  _everything_ came flooding back.

The ‘poison’ … His mistake … His brother dusting … and Sans.  Sans. Sans.

 _Sans_.

It was once his own name… and now it was the source of his grief and suffering. All of this was because of him.  _All of it_.

Even the …

Red sat up, looking down at his large belly. Finally understanding why everything had been feeling wrong—why he had been so uneasy.

But no.

He wasn’t going to make a mistake.

Slowly standing and using the toilet as he leverage, he headed towards the sink.

This was still his house after all, so there was no way that Sans would’ve been able to know that he there was a secret compartment right under it. It was for emergencies to protect his baby brother …

 _Papyrus_. He grabbed the switchblade and flicked it, admiring its sharpness. He’ll end it.

He moved so that his back pressed against the wall, determined to set things right.

Red looked back down, lifting his shirt up to see the small purple soul beating in his abdomen. One would think there would be guilt. One would think there would be regret; some sort forlorn expression he’d sport toward his kin.

But he stared at it with cold eyes before covering his stomach.

Hands grasped tightly at the blade, pointing it to himself.

“Papyrus … I’m sorry too.”

And he plunged it deep. His blood spilling copious amounts and he spat out some from his mouth.

With the deed done, he dropped the weapon, the resounding clang was comforting.

He was at peace and slowly closed his eyes.

* * *

 

Red awoke to find himself on a bed. Disoriented and confused at his current situation.

 _What_ —

“Good morning, love.”

Red stilled, his eye lights narrowing as he turned his head.

He began to tremble uncontrollably when the monster began to move towards him. His demeanor was not as friendly as it had been.

“It was unfortunate that you had a miscarriage, Red. I really thought I was going to lose you.”

The skeleton stood before him, staring him down, the smile still present but the warmth was nonexistent.

“I believe I’ve told you many times before Red.” A hand caressed his cheek and all he could do was shudder in fear.

“ _No one will separate us_.”

There was no escape. He truly was in hell.

**Works inspired by this one:**

  * [A Cure for Obsession](https://archiveofourown.org/works/15108173) by [Whosthisnerd](https://archiveofourown.org/users/Whosthisnerd/pseuds/Whosthisnerd)




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